Numerous piping systems typically are included in nuclear reactors. Such piping systems are utilized, for example, to deliver feedwater to the reactor pressure vessel (RPV) and to deliver steam from the RPV to a power generator. Numerous pipes typically extend throughout the reactor and sometimes are located in crowded spaces with many other pipes and other reactor equipment.
Over the life of the reactor, reactor piping systems may be modified, upgraded, repaired or replaced. When performing such tasks, it often is necessary to weld, or join, the pipes of the particular piping system. It is desirable, of course, that such welds be of high quality to prevent the leakage of reactor water. It also is desirable to use automated welding equipment to facilitate repeatability of high quality welds and also to decrease operator exposure to radiation.
Known and commercially available automated welding equipment generally can be used to perform a wide range of pipe joining applications. In-situ equipment clearance requirements in nuclear reactor welding applications, however, are more limited than in many other pipe joining applications. As a result, to use the known automated welding equipment in a nuclear reactor application, peripheral system interferences (e.g., other reactor components) often must be removed and then, after completing the welding operation, reinstalled into the original configuration. Of course, removing reactor components so that a weld operation can be performed and then reinstalling the components in to the original configuration increases the time required to complete the operation. Increasing the time required to perform the weld operation typically results in increased reactor shut-down time and increased operator radiation exposure.
In addition, in some circumstance, the reactor component configuration simply cannot accommodate the welding equipment. Under such circumstances, a worker typically manually performs the weld operation. Of course, requiring a worker to manually perform the weld operation increases the potential for reduced quality and also increases the worker radiation exposure, which is undesirable.
It would be desirable to provide an automated weld assembly particularly suitable for use in nuclear reactor applications having minimal axial and radial clearances and which is easy to install and controllable for forming high quality welds. It also would be desirable to provide such a weld assembly capable of being securely mounted in very restricted spaces, or envelopes, and which is easily configured for many different set-up circumstances.